Diesel engine



Aug. 19, 1941. c. -A.BALTON DIESEL ENGINE Filed Sept. 11, 1939 12 Sheets-Sheet 1 vAug. 19, 1941} c, A. BALTON 2,252,914

DIESEL ENGINE v Filed Sept. 11,v 1959 12 Sheets-Sheet 5 Au .19,1941. v- C A BAL O 2,252,914 I DIESEL ENGINE Filed Sept. 11, 1959 l2 Sheets-Sh'eet 4 J1 59 I (f9 J7 Aug. 19, 1941. C BALTQN 2,252,914

DIESEL ENGINE Filed Sept. 11, 1939 12 Sheets-Sheet 5 fir rap/rem Aug. 19,1941, @ABALTON -2,25 2,914

DIESEL ENGINE Filed Sept; 11, 1939 12 Sheet s-Sheet e 34 ai 7 t Bu Aug. 19, 1941. A TON 2,252,914

DIESEL ENGINE Filed Sept. 11, 19:59 12 Sheet-Sheet 7 r r I I my.

Aug; 19, 1941. v c. A. BALTON 2,252,914

' DIESEL ENGINE 2 Filqd Sept. 11, 1939 1.2 Sheets-Sheet 9 m afze:

FTTOFA/EYJ A 1 1941-, c. A. BALTON I 2,252,914-

DIESEL ENGINE! Filed Sept. 11, 1939 12 Sheets-Shot 11 i x 11mm x I flrrakn sys jivuzwrak center position.

Patented Aug. 19,1941

DIESEL ENGINE Charles A. Balton. Buflalo. N. Y., assignor to- Trans-America Aircraft and Motor Corporation, Tonawanda, N. Y., a corporation oi New York Application September 11, 1939, Serial No. 294,381

22 Claims. (01. 123-65) This invention relates generally to certain new and useful improvements in internal combustion engines, and primarily seeks to-provide a novel full Diesel engine structure designed'to operate on the two stroke cycle and which is particularly adapted for use as an aircraft engine oi the inverted, in-line type.

Heretofore, much difliculty has been encountered in producing .two cycle Diesel engines which would be satisfactory for use in aircraft. One of the principal objections has been the high weight-power ratio of engines of known form which rendered them too heavy and cumbersome for the use stated. This' was brought about by the necessity for using heavy structiiral par-ts in order to withstand the stresses the combustion chamber bearing projection on each piston is provided with a recessed chambeng the walls of which have a plurality of orifices I connecting the chamber with the air in the cylinder, said orifices being-so disposed as to cause jets of air to impact in the chamber as the piston approaches top dead-center whereby the temperature of the air may be raised to a high pre-combusticn chamber formed in each piston developed due to the very high compression ratios essential to secure ignition of the injected fuels in operations under the full Diesel principle. Another objection present in engines of known forms has been the ineiflciency in scavenging due to improper handling and injection of the scavenging air. Another objectionhas been presented by loss of efficiency in precombustlon chambers due to the impossibility of properly'scavenging such chambers during operation.

Also, in previously known engines, the desired is connected to one or more air ducts adapted to register with associated scavenging ports during scavenging to effect thorough cleaning of burned gases from the pre-combustion chamber. and to replace said burnt gases with fresh air. thereby increasing the efllciency of the engine.

A further object of the invention is to provide an engine of the character stated in which air is handled in two adiabatic stages, the first being a scavenging stage at pressures slightly above atmospheric, and the second being a supercharging stage in which the 'air is admitted to the cylinder following scavenging and under pressures appreaching two atmospheres.

compactness of structure could not be obtained A further object ofthe invention is to provide an engine of the character stated in which the scavenging and supercharging air is handled in triple thermo-dynamic-sequence including isothermal scavenging before the exhaust valve cooling principle being so bulky as to ofler too much resistance to movement'through the air.

The above mentioned andother diiilculties experienced in previously known engines have been overcome through the development of the structural features and equipments herein disclosed. Therefore, anobject of the invention is to provide a novel inverted in-line engine structure particularly adaptable for use in aircraft and which operates on two stroke Diesel cycle.

Another object of the invention is to provide an engine 01' the above mentioned character in which each piston is provided with a diametrical rib-like projection extending in the direction of the axis of the piston and formed to provide a pre-combustion chamber, and adapted to be received into and substantially fill a recess in the cylinder head as the piston approaches top dead- Another object of the invention is to, provide an engine of the character described in which closes, adiabatic charging after the exhaust valve closes, and a diabatic supercharging following completion of scavenging.

A further object 0! the invention is to provide an engine of the character stated in which the air for supercharging is passed through an intercooler prior to inder.

A further object ofthe invention is to provide an engine of the character stated in which the air for scavenging and supercharging is handling by a two stage centrifugal pump, the first stage of which is connected to the scavenging ports of the engine through a rotary valve for low pres sure scavenging, and the second stage of which is connected to the intercooler and through said admittance to the individual cylintercooler and individual poppet valves therein I with the supercharging parts of the engine for controlling the admission of high pressure air for second stage adiabatic supercharging.

A still further object or the invention is to provide an engine of the character stated which is both air and liquid cooled in a novel manner.

A still further object of the invention isto pr vide an engine of the character stated in which the air cooling is effected through the medium of a plurality of heat dissipating fins disposed in a novel manner, and the liquid cooling is eifected through the use of a full jacketed type of engine structure in which a liquid coolant is circulated under pressure within the engine itself, there beof Figure 10.

ing no auxiliary radiators used during normal operation of the engine.

A still further object of the invention is to provide an engine of the character stated in which the liquid coolant circulating system thereof is provided with a thermostatically controlled bypass for diverting the flow of liquid coolant through a sniall auxiliary radiator, should thewhereby any corrosive compounds formed in the crankcase as a result of operation will be drawn therefrom, thereby avoiding the formation of sludge in the crankcase.

A still further object of the invention is to provide an engine of the character stated in which the individual pistons are provided with removably mounted and interchangeable com-- 'bustion chamber forming piston heads.

A still further object of the invention is to provide an engine of the character stated in which the pistons arefull skirted and present a smooth surface to the cylinder w-alls,.unbroken by piston pin apertures or the like.

with these and other objects in view which 'will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure l is a side elevation of an engine constructed in accordance with. the invention.

Figure 2 is a rear elevation of the engine.

Figure 3 is a front elevation of the engine.

Figure 4 is a vertical transverse section taken on line 4-4 of Figure 1.

Figure 5 is a somewhat diagrammatic horizontal section illustrating the two stage pump and the connection thereof with the flow controlling valves, the section taken generally on the line 55 of Figure 4.

Figure 6 is an inner face view of the intercooler per se.

Figure 6 is an end elevation ofthe intercooler per se.

Figure 7 is a diagrammatic fragmentary sectional view, showing the position of the piston during supercharging.

Figure 8 is a fragmentary sectional view showing the relation of one of the pistons to the cylinder head.at the moment of injection.

Figure 9 is a fragmentary sectional view taken at right angles to Figure Band showing the location of the port plugs relative to the piston tongue. V y

Figure 10 isan axial section through a piston having one form of pre-combustion chamber casting secured thereto.

Figure .11 is a side elevation, partly in section, of the piston of Figure 1 0. v

Figure 12 is a bottom' plan view of the pistbn Figure 13' is a top Fi e 10.

Figure 14 is a diagrammatic view illustrating the liquid coolant by-passlng system.

Figures 15, 16, 17 and 18 are fragmentary sectional views illustrating various individually modified forms of pre-combustion .chambers.

' Figure 19 is a fragmentary sectional view taken at right angles to Figure 17.

. Figure 20 is a cycle diagram showing the se quence of operation of the engine.

Figure 21 is an enlarged fragmentary vertical cross section taken through the axis of one of the supercharging air admitting valves.

Figure 22 is an enlarged fragmentary side elevation illustrating the arrangement of the injector nozzles and the supercharging air admitting valve actuating rockers.

Figures 23 and 24 are somewhat diagrammatic views respectively illustrating, in side and end elevation, the driving devices for the air pumps,

the coolantcirculating pump, the rotary valve and the cam shaft.

In the drawings, the invention is. illustrated as embodied in an inverted, in-line engine operating. on the two stroke Diesel cycle. a

The engine includes a cylinder block 5 having a plurality of cylinders 6 formed therein, three such cylinders being shown in the example of embodiment herein disclosed. The upper end of the cylinder block is shaped to form the lower half I of a crankcase, the upper half of the crankcase being formed by the usual crankcase cover 8. The outer surface of the crankcase is provided with a plurality of longitudinally disposed, radially extending, heat dissipatingflns 9 integrally formed therewith. Similar heat dissipating fins 10 are formed integral with the cylinder block 5 on one side and the front and rear ends thereof, the other side of the cylinder block being without fins.

The cylinder block I and the complete crankcase I, 8 are provided with a full jacket Ii adapted to receive a liquid coolant. The coolant receiving jacket II, it should be noted, completely jackets the cylinders, the cylinder head, and the crankcase to thereby provide a uniform distribution of heat throughout the entire engine.

This uniformity of heat distribution has been found desirable in order to prevent sludge formation such as would be encountered in the absence of an eflicient jacketing of the nature stated, and means are provided for extracting from the crank case during operation of the engine vapors likely to present the problems of sludge formation, as will be hereinafter more fully described.

A gear housing I! is fitted to the forward end of the. crankcase I and rotatably supports the splined end of a propeller shaft it which projects axially therethroug'h. Y

.A liquid coolant circulating pump I, preferably of the centrifugal'type, is secured on the rear face of the engine adjacent the lower end.

thereof, and is adapted to be positively. driven by a suitable connection to a rotating part of the engine. The discharge side of the pump it is connected to the rear. end of the cylinder block adjacent the 'lower end thereof by a flow pipe or other conduit II, and a return pipe I, having its upper end connected to the coolant jacket at the rear end of the crank cover 8 and its lower end connected tothe intake of plan view of the piston of to be more fully described hereinaften Jacket H to complete the continuity of the cooling' circuita'The flow or the liquid coolant'during operation of the engine is from the rear of the engine to the front, andvfrom the bottom to the't'op. Along the top of the engine, the

how is from the front or the engine to the rear where thecoolant enters the pipe is and is.

directed by it to the pump for-recirculation.

A crank shaft I1 is rotatably supported by the crankcase I andis operativelyconnected to the plurality of pistons" through the medium oi. the usual connecting rods l9. The engine is also provided with the usual cam shaft It.

A rotary valve 2|, havinga plurality of valve ports 22, is rotatably mounted within a rotary valve casing 23 extending along one side of the engine. The casing 23 is in open communication with the cylinders 8 through the medium 01 short conduits 24 lnjFigure 21 joining the valve casing with a scavenging manifold 25 associated with and encircling each cylinder. Within each scavenging manifold 25 and passing throughthe respective cylinder walls are provided a plurality of circumferentially spaced scavenging ports 25 for admitting scavenging air to the cylinders.

Within each scavengingmanitold is also provided a pair of diametrically opposed ports 21 or cylinder wall passages for admitting scavenging air to the pre-combustion chamber formed in the particular cooperating'piston, in a manner The cylinder block 5 is provided with aplurality; of air ducts 28 formed therein and disposed in a plane slightly below the plane orthe scavenging manifolds 25. Each duct 28 com-- municates with the interior of a cylinder through a plurality of supercharging ports it for a purpose to be hereinafter described.

An air pump 30, preferably of the centrifugal type, is secured-"to the rear end of the engine near the bottom thereof, and includes a low pressure stage 3! having an impeller 32, and a high pressure stage 33 having an impeller tit. Air is drawn into the low pressure stage of the pump through a central air intake bell Most of the air drawn into the low pressure stage is dirested therethrough and discharged into a relatively large duct to connecting the low pressure invclute with the rotary valve casing- See Figure 5. The remainder of the air is directed througha Venturi duct 3'8 into the center intake oithe high pressure stage 33. The Venturi duct 3'! is provided on its outer surface with a plurality of spaced annular heat dissipating fins 3% which effect a cooling of the air as it enters the high pressure stage of the ump. The air entering the high pressure stage 83 has its pressure increased therein to a degree approaching two atmospheres and is discharged therefrom through a relative small duct 39.

The high pressure air duct 39 is connected to an inter-cooler element generally designated.

' to secured to that side of the cylinder clock not troduced through the high pressure duct 39. An

inner plate or wall portion 41 of the casting opposes an opening "in the jacketed cylinder block 5 and is held spaced from the block by the marginal flange portions 44 which surround said opening. A closure plate or gasket 45 is clamped between the flange portions and the block and serves as a closure for the block opening..- The plate, 45 is spaced from the wall portion 43 and is in heat exchange relation with the air freely circulating between it and said wall portion through the flange penetrating atmospheric air introducing and discharging ducts 46. .Heat dissipating fins 41 project inwardly and outwardly from the casting 4|. Valve supportiugand guiding structures 48 are Iormed'in the inter-cooler, one for each engine cylinde ,1 and a valve seat 49 cooperates with each said structure and provides a passage through which air can pass from the interior oi the inter-cooler through the respective inlet ducts, 28. .As the air passes through they inter-cooler, heat will be removed therefrom through expansion of the air and by dissipation through the 41 formed integral with the inter-cooling casting The inter-cooler, as a complete unit, is rigidly secured to the cylinder block 5 by a plurality of bolts 50, the intermediate hollow portion of the inter-cooler being additionally supported through the use of spacing elements formed between the plate itanol the plate 35. g

The admission of high pressure air-to. the cylinders through the supercharger portstt is controlled through the use oi valves Flt, illustrated in this particular disclosure as of the poppet type, one such valve cooperating with each seat to for controlling passage of air through each duct to and being actuated through suitable connections 52 with the cam shaft 2&3.

The engine operates on the full Diesel prio ciple and ignition and combustion is accomplishecl through the use of a novel piston carrie'd pro-combustion chamber and novel cylinder head structure. Each piston it? is provided with a cllametricai tongue-like projections extending downwardly in an axial direction from the piston head (see Figs. 4, 7 and it). The piston tongue to is provided with a chamber extending upwardly and axially from the bottom edge thereof.

- It is to he noted that the chamber $6 is of uni- The piston tongue form cross section when viewed in transverse section, and bulb shaped in longitudinal section. The upper extremity of the charnher 5G is disposed slightly above the plane of the piston head. The bottom oi the piston tongue 53; is seal lopecl to provide two concave bottom edge portions which are symmetrically disposed relative to the intake orifice oi" the chamber E3 2. $3 is also provided with a pair oi oppositely extending ducts which. connect the mid-portion oi the chamber with the respective bottom edge portions so to allow the passage oigases of combustion thcrethrough during ignition. r v

When "in. the operation of the engine a given piston approaches the top dead-center position,

its tongue is received into a recess 5'?! provided in the cylinder head, ticn with the piston chamber. I i

One side of each cylinder head recess 5i is provided with a pair or port plugs to thread ably engaged in the cylinder block. Each plug and forming, in conjunctongue a combustion 55 is provided with an inwardly projecting annular portion 59 disposed orifices dices .60 permit a having a plurality of radially EB formed therein. The oriiiow of air therethrough to the posed and axially extending inner portion of each annulus 59 and. efiect a material increase in velocity of the air. The individual jets of air passing through the orifices mutually impact at a substantially common point. Thus the increased velocity of air passing through the orifices plus the effect of mutual impact of the individual jets raises the air to a materially higher temperature thanwould result from conventional compression of the air. It may be found desirable to use a metallic wool, such as copper wool, in-- each annulus 59 which would glow due to the rise in temperature and effect a flashing of the cylinder charge. The port plugs 58 in each cylinder are so disposed that when the particular piston reaches the top dead-center position the concave bottom edge portions 55 of the piston tongue are disposed in substantially concentric relation thereto and are spaced slightly therefrom in order to form an annular combustion cavity surrounding each plug.

Air ducts 6| extend through the piston tongue 53 from the diametrically opposite edges thereof, and extend into open communication with the chamber 54. These ducts 6| are adapted to register with the small scavenging ports 21 in' order to effect proper scavenging of the chamber 54 and to substitute fresh air for the burned gases therein. e

Each cylinder is also provided with an exhaust valve 62 operatively mounted in the cylinder head and located in the wall of the cylinder head i 3 recess 51 on the side opposite the pbrt plug 58. Each exhaust valve 62 is actuated from the cam shaft 20 through the medium of suitable cam, rocker and tappet equipments generally designated 63.

Fuel is injected into each cylinder through a nozzle equipment 64 which preferably is posi-- tioned to inject fuel in an axial direction into the mouth of the piston chamber 54 as the piston approaches top dead-center position. See Figures 8 and 9. f

In Figure of the drawings there is illustrated a modified form of piston-carried tongue and combustion chamber arrangement in which the tongue which is similar to the piston tongue 53 above described, but does not include the air ducts leading to the chamber 54 for the specific scavenging of that chamber.

In Figure 16 of the drawings there is illus- 1 trated further modified form of piston-carried vided with a jet" diverting ate end portion II formed in one side wall'thereslot it having 'an arcuof. Anoriflce I2 is' formed in the opposite wall of the chamber 69 and is adapted to register with a. laterally disposed injection nozzle .13 as the piston approaches top dead-center position. The

upper end of the chamber 66 terminates in a laterally extending T-section 14 formed in the piston body slightly abovepthe plane of the pis- ,ton head. The chamber 56 is also provided with 1 airducts I5 communicating therewith from the v diametrically opposed side edge portions of the piston tongue 65 and adapted to register with the small scavenging ports 21 of the respective cylinder as the piston approaches bottom deadcenter position to thereby rid the chamber 65 of the gases of combustion and replace them with fresh air. See Figure 4.

In the above described form of pre-combustion chamber, as a given piston approaches the top dead-center position, the tongue 65 is received into the associated cylinder head recess 51, and the air confined in the space between the bottom v edge portions of the piston tongue and the cylinder head recess is rapidly compressed to a high pressure and temperature. The temperature of the air is additionally raised by the flow thereof under the force of compression through the orifices 61 and the'mutual impact of the orifice air jets within the chamber 69, thereby obtaining a temperature greater than would be achieved through conventional compression. a

In Figure 19 of the drawings, there is illustrated an additional modified form of pre-combustion chamber which is somewhat similar to that disclosed in Figures 4, 16 and 17. In this particular form, the bulb-like chamber 54 is provided on one side with a relatively short arcuate jet diverting sector or wall portion 16 having a radius of curvature difierent from that of the remainder of the chamber and disposed in opposed relation to an injection orifice 11 extending through the opposed wall of the chamber.

tongue and combustion chamber arrangement in which the tongue is similar to that described hereinbefore but does not include the air ducts. leading to the chamber 54, nor are there included the previously mentionedinwardly extending port plugs. v

In Figures 17 and 18 of the drawings there is illustrated a modified form of pre-combustion chamber in which said chamber is formed wholly within the piston and the axially extending pis- The orifice I1 is adapted to be disposed in register with a laterally disposed injection nozzle, such as was described in conjunction with Fig, 18, as the piston approaches the top dead-center position.

It is to be noted that through the use of the above described forms of piston-carried precombustion chambers it is only necessary to use a compression ratio of approximately mag-13:1

Y in the cylinders in order to obtain a degree of heat in-the ire-combustion chambers for proper ignition substantially equivalent to the heat obtained in such engines of present, form having a compression ratio of 16.411. Therefore, the use of the considerably lower compression'ratio in this engine enables the provision of a much lighter engine structure than has been practical heretofore and also provides for a lower weightper-horse power ratio. The use of the lower compression ratio isal'so beneficial to the indicated B. P. (brake 'mean eifective pressure). The pistons l8 embrace certain novel features of construction and are of the blind type. They are assembled with the connecting rods and then the skirt is pulled up into place and bolted by four bolts to insure rigidity during operation. Each piston I8 is a frabricated structure comprising fc-ur interchangeable units, namely, a skirt casting I8, a pre-combustion chamber a piston ring collar 8|.

tures or the like. crown casting, the forms of piston tongue com- The skirt casting I8 is cylindrical in form and has its wall section internally flared from head to base. The inner surface of the skirt is provided near the base with two sets of diametrically opposed heat dissipating fins 82 formed integral therewith. The inner surface of the skirt is also provided with' four circumferentially spaced bolt-receiving lugs 88 formed integral therewith and disposed in spaced relation above the fins 82. A circumferential groove 84 is formed in the outer surface of the skirt near the base end thereof for receiving an oil-seal pistonring. The head of the skirt unit I8 is counterbored to provide a seat II for mounting the wrist pin casting 80.

The wrist pin casting 801s a cylindrical casting having an outside diameter for snugly fitting the counterbored-seat 88 formed in the skirt unit. The base of the wrist pin casting is adapted to flt into the seat 88 and be retained therein by means to be hereinafter described. Thehead 88 of the wrist pin casting is substantially flat, and

- is reinforced on its inner side by a plurality of spaced depending webs 81 formed integral therewith. Wrist pin bearings 88 aremounted on depending portions 88 of the wrist pin casting, said depending portions 89 being supplemented by a yoke-like web 90. Four axially extending internal extensions 9| merging into a like number of external depending sleeves 92 are provided within the wrist pin casting and are disposed to register with the skirt lugs 89 when the piston is completely assembled. The casting head 88 is provided with a circumferential recess 93 adapted to receive the inturned flange of the piston ring carrying collar. formed on the outer surface of the casting head 86 The interchangeably mounted crown casting I9 is provided with a selected one of the forms of diametrically disposed and axially extending combustion chamber tongues hereinbefore described. The crown casting is mounted on the head 88 of the wrist pin casting and may be provided with a counterbore 95 adapted to fit over the centering ring 94 on the head 88-. It should be noted that the ring 94 may serve the additional function of sealing the counterbore 95 to thereby form a closed combustion chamber portion such as has been described as the T-section chamber portion It in conjunction with Figures 17 and 18. c

The collar BI is clamped in position by the crown casting I9 when the parts are assembled and it is provided with a plurality of circumferential piston ring mounting grooves 98 in which the usual piston rings 91 are mounted.

The entire four casting piston assembly is rigidly secured through the use of 'four tie bolts 98 extending through the crown casting, the mounting extensions SI and sleeves 92, and the lugs 83 of the skirt. A suitable oil ring may be mounted in the groove 99 formed between the lower end of the skirt I8.

Several advantages are obtained through the the collar 8| and the upper end of use of pistons constructed in the manner described. Through the use of such construction,

'a full skirted piston is provided in which the skirt portion presents a smooth surface to the cylinder wall, unbroken by any wrist pin aper- Also, by having a removable A centering ring 94 is torrid weather, it may be found desirable to provide a small auxiliary radiator assembly con nected in series with. the liquid coolant circu lating system, in order to more efiiciently cool the engine. Such an auxiliary cooling assembly is disclosed in Figure 14 oi the drawings. The small core radiator I00 is adapted to receive liquid coolant from the discharge orifice of a bypass valve i0I through a conduit I02. The bypass valve IOI is connected in series with the coolant return pipe I8 and is located near the upper end thereof. The by-pass valve includes a valve member I08 adapted to be controlled through the medium of a heat sensitive bellows I04 containing ethyl alcohol or the like. When the auxiliary cooling assembly is installed, the lower end of the coolant return pipe I8 is connected to the stem ofa T-couplin'g I05.- Then a short connector pipe I8" has one end secured to one arm of the T I05 and its other end to the coolant circulating pump II. The lower end of,

through the pipe I02 to and through the radiator I00. The coolant re-enters the circulating system from the radiator through the pipe I08 and the 'r-coupling I05 By diverting a portion of the liquid coolant through the auxiliary radiator I00 while operating in torrid zones, suflicient additionahcooling efl'ect is obtained to maintain the temperature of the entire amount of coolant V at the proper level for the most eiiicient operation.

Means are provided in this engine for withdrawing from the crankcase, all gaseous vapors which, if retained in the crankcase, would tend to form corrosive sulphurous compounds and sludge, to the detriment of the engine. The rear end of the crank case I is provided with a hand hole cover I01 removably secured thereto and provided with a downwardly extending projection I08 having an orifice formed therein. A

crankcase breather tube I09 has one end secured within the projection I08 and its other end connected to the intake annulus 35 of the air pump 30. Thus as the engine is in operation, the reduced pressure at the air pump. intake annulus will cause a flow of gaseous vapor from the crankcase through the breather tube I09 into the air pump. These vapors then pass through the engine and are exhausted into the atmosphere, thereby maintaining a relatively clean crankcase.

It will be observed by reference to Figures 2 and 14. of the drawings that the'coolant return line preferably includes a resistance check valve generally designated II 0. This valve serves to maintain the'coolant under an eight pound presbustion chambers are interchangeable at the opconductivity from cylinder walls to skin of jacketing is increased. I

In Figures 23 and 24 of the drawings I have somewhat diagrammatically illustrated driving connections for the air pumps 80, the coolant circulating pump II, the rotary valve 2| and the outer cleaner scavenging is facilitated.

the cam shaft 20. The crank II carries a large dagger gear III and a smaller driver gear H2 which are rendered selectively effective for imparting variable speed rotation to the driver gear through the driven gears H4 which mesh with the gears IIIand I12 and are selectively connected in drivingrelation with said gear M3 by any suitable shiftable clutch devices generally designated H6. The gear I13 imparts .its rotation to a driven gear II6 secured on a shaft II! which also carries alarge gear H8. The gear I I6 meshes with a small gear I I9 on the impeller shaft I of the first stage impeller 32 and drives that impeller below sound speed. The shaft I20 also carries a gear I2I which meshes with suitable intermeshing speed increasing gears- I22 1 through which the rotation of the shaft I26 is imparted to the sleeve I23 on which the second stage impeller 34 is mounted, so as to drive that impeller above sound speed. The gear I II also drives a gear I24. The gear I carries a bevel gear I25 which meshes with a like gear I26 on a vertical shaft I21 from which rotation is imparted to the cam shaft 20, throughsuitable gearing I28, and to the coolant pump l4, through suitable gearing I29.

By placing the valves 5| directly in the intercooler, the length of the air ducts 28 leading to the supercharge ports 29 is reduced and reheating of air within said ducts is minimized. These air ducts 28 also retain air when the ports 29 are closed by the pistons and this entrapment of air serves to dilute the gases of combustion near the end of the power strokes after the piston heads have cleared the supercharge ports 29, and. thereby exhaust smoking is decreased and It is preferred that all cooling fins be coated with material having a great aflinity for infrared rays so as to facilitate heat dissipation outwardly.

In order to properly describe the operation of the engine, one complete cycle of operation in a single cylinder will be explained. For a convenient starting point, it will be assumed that the piston I6 is moving toward the bottom deadcenter position on the power stroke. When the piston reachesa point 79 before bottom deadcenter the exhaust valve 62 opens'to begin the exhausting of the burned gases of combustion. At a point before bottom dead-center, the scavenging ports- 26 are uncovered by the piston, and the rotary valve 2| functions to admit scavenging air therethrough. It should be noted that the scavenging air from the low pressure stage of the air pump enters the cylinder at a pressure of approximately 9 pounds per square inch gage, thereby effecting a positive scavenging through the entire cylinder.

As the piston uncovers the scavenging ports 26 during its movement, the scavenging ducts 16 in theijpiston tongue 53 register with the small scavenging' ports 21 to allow specific scavenging of the piston carried pre-combustion chamber.

'When the piston reaches bottom dead-center the power stroke, is completed and the compression stroke begins. After the piston moves 22 past bottom dead-center position the exhaust valve closes, but air still enters the cylinders through the scavenging ports 26. It should be understood that from the position 55 before bottom dead-center to the position 22 after bottom dead-center the scavenging air entering through the ports 26 is actually charging air admitted under an adiabatic state since the exhaust valve had been closed at the beginning of that period and from that time on both the pressure and temperature of the air progressively increased. This air is now undergoing additional compression as a result of the piston travel towards top dead-center position.

At the point 55 after bottom dead-center the poppet valve 5| controlling the supercharge air from the high pressure stage of the air pump is opened to admit supercharge air into the cylinder through the supercharge ports 29 which have not been covered by the travel of the piston towards top dead center. This supercharge air is admitted to the cylinders under a pressure approximating two atmospheres, and enters the cylinders in an adiabatic state. When the piston reaches a point 79 after bottom dead-center, the supercharge ports 28 have been closed by the piston and the poppet valve 5| seated to close of! the how of air to the supercharge ports. Thus it will be observed that the supercharge air has been admitted to the cylinder through 24 of tion, the air in the cylinder is subjected to the usual compression. However, fuel imection should'be controlled to begin at a point 30 before top dead-center for take ofis, or 22 before top dead-center for cruising,and to end 11 after the top dead-center position. The power stroke is then beginning and the cycle is repeated.

It should here be observed that through the use of charging and supercharging air admitted to the cylinder in an adiabatic state, as differentiated from similar air admitted in an isothermal state, a more efficient cycle of operation is achieved thermodynamically.

It should be noted that the particular two stage air pump 30 illustrated handles 712 cu. ft. of air per minute, 500 cu. ft. of which is drawn from the lower pressure stage 8| for the isothrough the inter-cooler 40 where it is expanded to about one and one-half times its entering volume in-order that the air may be admitted to the cylinders in a fully expanded state. This avoids any potential decrease in amount of supercharge air in the'cylinders ,due to expansion upon admittance to the cylinder. 1

It will'be readily apparent, by reference to the cycle diagramillustrated in Fig. 20 'of the drawings, that by forming and controlling the engine bottom dead-center,the scavenging air is'adso as to operate. in cycles as described and diagrammatically illustrated, there will be no overlapping of scavenging and supercharging air in isothermal and adiabaticstates respectively, nor will there be any gaps between scavenging and supercharging air. Therefore, by providing a smooth continuous sequence of air control and, admission to the respective cylinders, a higher thermodynamic eiiiciency will be obtained than is possible of attainment in engines not operating under the above mentioned conditions.

Thus it will be seen that the invention provides a novel invertedin-line internal combustion engine operating on the two stroke Diesel cycle which is provided with a novel form of piston carried pre-combustion chamber; in which the cycle of operation includes isothermal scavenging, adiabatic charging, and adiabatic supercharging; which is provided with a combined air and liquid cooling system, and which is simple in design and rugged in construction. In this disclosure broad references have been made to air pumps, but it should be stressed that advantages are obtained by utilizing superchargers which develop constant pressures as distinguished from pumps of a nature likely to set up pulsations.

While the principles of the invention are herein stressed as embodied in an aircraft engine of the inverted,-in-line type, it will be obvious that these principles can as well be applied to engines which are not inverted and which are used for purposes other than in aircraft, and which have their cylinders arranged in radial or other not in-line forms.

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without'deiplanting from the spirit and scope of my invenon. i

I claim: 5

1. In a two cycle Diesel engine, a plurality of cylinders, a piston reciprocable ineach' cylinder,

a crank shaft, pitmen connecting the pistons with the crank shaft, means for injecting fuel into air compressed in said cylinders, an exhaust valve in each cylinder, each said cylinder having a set of scavengingand charging air ports and a set of supercharging air ports opened and closed by movement of the pistons, means for opening each exhaust valve before the associated piston uncovers the scavenging and charging ports onits power stroke and for closing said valve before said piston closes these ports on its compression stroke, means for forcing air through said scavenging. and charging ports at low pressure while said exhaust valves are open and therespective pistons uncover these ports, and means for immediately thereafter forcing supercharging air through the supercharglng ports whereby there will be no overlapping of scavenging and super-- charging air in isothermal and adiabatic states respectively and no gapsbetween scavenging and supercharging. e

2. An engine structure as defined in claim 1 in which a rotary valve controls the admission of I air through the scavenging and charging ports,

and a poppet valve controls the admission of air through each set of supercharging ports, and in which a single constant pressure pump delivers air to all said ports, at low pressure to thesc'avenging and charging ports, and at high pressure to the supercharging ports.

3. An engine structure as defined in claim 1 in which the supercharging air is delivered to the supercharging ports through an intercooler chamber wherein it is expanded and cooled'prior to passage through said supercharger ports.

4. An engine structure as defined. in claim 1 in which a rotary valve controls the admission of air through the scavenging and charging P rts, and a poppet valve controls the admission of air through each set of supercharging ports, and in which the supercharging air is delivered to the supercharging ports through an intercooler chamber wherein it is expanded and cooled prior to passage through said supercharger ports, ,said poppet valves being mounted in said intercooler chamber.

5. In a two cycle Diesel engine, a plurality of cylinders, a piston reciprocable in each cylinder, a crank shaft, pi-tmen connecting the pistons with the crank shaft, means for injecting fuel vinto air compressed in said cylinders for a short I interval before and after each respective piston reaches top dead-center, an exhaust valve in each cylinder, means for opening each valve from approximately 79 before the respective piston reaches bottom dead-center until approximately 22 after the respective piston passes bottom dead-center, means for delivering air at approximately Qpounds pressure into each cylinder during the time the respective piston is passing from approximately 55 before bottom dead-center to approximately 55 past bottom dead-center, and means for delivering super.-

. charging air at a higher pressure into each cylinder d 'ring the time the respective piston is passing from approximately 55? past bottom dead-center to approximately 79 past bottom dead-center,

ch the supercharging air is delivered through an intercooler chamber wherein it is expanded and cooled prior to passage into the cylinders.

8. An engine structure 'as defined in claim 5 in which the air delivering means includes a single two phase pump for delivering the low and high pressure air at constant pressures from its respective phases, and individual control valve means for controlling the flow of the low and high pressure-air supplies respectively, and in which the supercharging air is delivered through an intercooler chamber wherein it is expanded and cooled prior to passage through the supercharging air controlling valves, said last named valves being mounted directly in said lntercooler chamber.

9. An engine structure as defined in claim 1 wherein is provided means for trapping a quantity of supercharging air outside each set of supercharging ports as the respective piston covers these ports to be available as said piston again uncovers these ports on its powerstroke to dilute burnt gases and minimize smoking and facilitate scavenging.

10. In a two cycle Diesel engine, a plurality of cylinders, a piston reciprocable in each cylinder, a crank shaft, pitmen connecting the pistons with the crank shaft, means for injecting fuel into air compressed in said cylinders, an exhaust valve in each cylinder, means for deliv-p .ering scavenging and charging air into said cylinders, means for delivering supercharging air.

into said cylinders, and an intercooler through which the supercharging air passes to the cylinders and in which it is expanded and cooled, said intercooler comprising a hollow relatively flat body lying substantially parallel the axes of the cylinders and spaced. therefrom so as to present inner andouter, top and bottom and front .and rear end surfaces forair cooling purposes.

11. In a two cycle .Diesel engine, a plurality of cylinders, a piston reciprocable in each cylinder-,a crank shaft, pitmen connecting the pistons with the crank shaft, means for injecting fuel into air compressed in said cylinders, an. ex-

. valves for controlling admission of the supercharging air mounted directly in the intercooler.

relation into each of said communicating com.- bustion chamber portions, each said plug having a plurality of small orifices therein through which air compressed in'said chamber portions rushes into the interior of each plug in very high velocity impinging jets.

,17. An engine structure as defined in claim 12 inwhich each cylinder includes a scavenging air 12. In a two cycle Diesel engine, a plurality of cylinders, a piston reciprocable in each cylinder, a crank shaft, pitmen connecting the pistons with the crank shaft, each said piston having a narrow tongue projecting from its free end in the plane occupied by the piston axis and extending from side to side of .the piston, each cylinder having a combustion chamber forming recess for snugly receiving the respective piston tongue,

' each said piston having a precombustion chamber therein formedin part in its tongue and in-' cluding a fuel receiving opening, an exhaust valve operable in each cylinder recess, and fuel injecting means directed into each recess for injecting fuel into the respective piston opening in said recess. g

13. An engine structure as defined in claim 12 in which each cylinder includes a scavenging air admitting port opened and closed by piston move--' ment, and in which each piston tongue has a scavenging duct therein opening through its side and registrable with the scavenging port for effecting a scavenging of the respective precombustion chamber.

' the cylinder, and each said fuel injecting means and cooperating piston opening being aligned on the respective cylinder axis.

.16. An engine structure as defined in claim 12 in which the opposed faces of 1 each cooperating tongue and receiving recess are complementarily formed to provide between them two substantially cylindrical communicating combustion chamber portions each disposed' at one side of the axis of the cylinder, each said fuel injecting means andcooperating piston opening being aligned on the respective cylinder axis, and in which :a holadmitting port opened and closed by piston move-- ment, and in which each piston tongue has a scavenging duct therein opening through its side and registrable with the scavenging port for effecting a scavenging of the respective preconibustion chamber, and in which a hollow cylindrical igniter plug projects in spaced relation into each of said communicating combustion chamber portions, each said plug having a plurality of small orifices therein through which air compressed in said chamber portions rushes into the interior of each plug in very high velocity impinging jets.

18. In a two cycle Diesel engine, a plurality of cylinders, a piston reciprocable in each cylinder, acrank shaft, pitmen connecting the pistons with the crank shaft, means for injecting fuel into air compressed in said cylinders, an exhaust valve in each cylinder, valves controlling introduction of charging and scavenging air to said cylinders, casing structure providing coolant j acketing about each cylinder, the various valves and the crank,

shaft, a conduit for taking coolant from a high point in the jacketing and delivering it to a low point in the jacketing, means for circulating ing conditions of abnormal heat to by-passthe coolant through said radiator.

19. In a two cycle Diesel engine, a plurality of cylindersfla piston reclprocable in each cylinder, a crank shaft, pitmen connecting the pistons with the crank shaft, means for injecting fuel into air compressed in said cylinders, an exhaust valve in i each cylinder, valves controlling introduction of charging and scavenging air to said cylinders, a pump for forcing air into said cylinders through said valves, casing structure providing coolant 1 Jacketing about each cylinder, the'various valves and the crank shaft, a conduit for taking coolant froma high point in the jacketing and delivering it to a low point in the jacketing, means for circulating coolant directly through the Jacketing and conduit under normal running cnoditions oi the engine, an auxiliary heat exchange radiator, thermostatically controlled means effective during conditions of abnormal heat 'to by-pass .the coolant through said radiator; and means for withdrawing vapors from the space surrounding the crank shaft and delivering it into the intake to said pump.

20. An engine structure as definedin claim 1 in which means is provided for withdrawing vapors from the space surrounding the crank shaft and introducing them into the cylinders along with the air for scavenging and charging the same. 21. In a twocycle Diesel engine, a plurality of cylinders, a piston reciprocable in each cylinder,'

a crank shaft, pitmen connecting the pistons with the crank shaft, means'for injecting fuel into air compressed in said cylinders, an exhaust valve in each cylinder, valves controlling introduction of charging and scavenging air to said cylinders, casing structure providing. coolant jacketing low cylindrical igniter plug projects in spaced" about each cylinder, the various valves and ,the 

